The communication protocol provides the rules for communication. The protocols govern the behavior of each communicating node on how to access the network, how to signal other nodes of its current situation and need, how to transfer data, and unique to a multiple access network, how to detect and resolve contention (often called collision). To help manage the complexity of a communication system, it is customary to divide the functionality of a communication system in layers of protocols. The International Standard Organization has specified seven layers from lower to higher: physical, media access control (MAC) or link, network, transport, session, presentation, and application layers. The present invention deals mostly with the physical layer for multiple channels and the MAC layer protocol for access. The management issue, including quality-of-service (QoS) policy, is a concern to be dealt with by the higher layer protocol. The bandwidth of communication network is normally separated into two types of channels—signaling and traffic bearer. In some multiple access networks, e.g. Carrier Sense Multiple Access with Collision Detect (CSMA/CD), these two types of channels are one and the same.
Communication systems with multiple access network have been providing satisfactory services in many markets, such as local area network (LAN), cellular telephony, and more recently broadband network based on CATV infrastructure. More recently, galvanized by the potential of a broadband network, cable modems conforming to CableLabs' Data Over Cable Service Interface Specification (DOCSIS) have been deployed in increasing numbers. These multiple access protocols provide satisfactory services when the network load is light (actually these networks are considered unstable if the usage reaches 80% of the maximum network throughput). Even with a light network load, there is no guarantee of QoS in these multiple access networks. At the same time, there is increasing pressure to put time-sensitive services, such as voice and video, on these networks. Moreover, during contention resolution phase, the services are interrupted.
The present invention overcomes the aforementioned limitations with the following objects:                Efficient and flexible use of communication facilities;        Compatible with and complementary to existing protocols;        Enabling various service quality levels; and        Providing seamless growth path.        
Further objects and advantages of the present invention will become apparent from a consideration of the drawings and ensuing description thereof.